Skanska leads 3D printing on the City of London building

Skanska, a world leading project development and construction group, uses 3D printing technology in the construction of its £50m Bevis Marks development in the City of London.

A Skanska-built office project has achieved an industry first by taking 3D printing out of the research labs and into a live project environment. The 6 Bevis Marks project boasts 3D printed cladding “shrouds”, were delivered to site last week and installed by Skanska this week, for the top section of tree-like steel columns supporting an ETFE roof on the building’s roof terrace.

We’re very excited by it – it’s the first time the company has used the technique,” says Skanska project manager and innovation champion Jonathan Inman. “But we’re currently talking to other clients about other opportunities for 3D printing.

Skanska’s innovation manager Sam Stacey added: “It’s something we are very interested in, we will look for opportunities and respond vigorously as they emerge.”

Simon Hammond, regional sales manager, says that Quickparts has been quietly innovating while others have been noisily discussing: “What people see in the news or on the BBC represents the consumer end of 3D printing, the machines you can buy for the home or office. But we’re a commercial bureau, we print parts for human bodies or parts of aeroplanes or Formula One, and they’re not prototypes – people are adopting 3D printing because of the advantages it brings.

“3D printing is not here to replace traditional manufacturing, but it does go through the ceiling of what you can do cost effectively. It comes into its own when a low volume production run [using conventional manufacturing] is prohibitively expensive.”

Bevis Marks was an ideal candidate for 3D printing, due to the complexity and lack of repetition in the design. “With eight different iterations, other types of manufacturing would need eight different moulds, but we produced eight unique [cladding] shrouds, according to CAD specifications.”

“We took the CAD file from the architect, then ‘sliced’ it into 0.1mm layers. The laser operates above a movable platform, so it traces one slice of the layer by putting enough heat on the nylon to melt it. Then the platform moves down by 0.1mm, you put on more powder and built it up layer by layer,” says Hammond.

The eight cladding nodes, entitled “shrouds”, were printed in different parts to be jointed and at last the 600mm wide, 800mm high nylon shrouds were completed and painted to resemble steel. Skanska naturally had reservations since the product did not carry any classic warranties.

“The material had not previously been used in an external environment, we needed a lifespan of 10-20 years, and there were also issues about the joints,” says Skanska’s Inman.

However, Quickparts and Vector Foiltec authorized hastened exposure testing to simulate the rain, sunlight and heat in the open-ended atrium, and they reported that the shrouds performed well.

“The architects were quite concerned about it, but they realised the technology is pretty well tested in other industries, and Quickparts were dealing with the testing in an appropriate way,” says Inman.

Hammond says Quickparts is optimistic that Bevis Marks could open the door to further work in construction, albeit in non-structural applications.

“We’ve got the confidence now because the material has been confirmed as OK – we have the certification and evidence. We understand that this is a big deal for construction clients.” As well as nylon, Quickparts can also print in a range of plastics and metals, including stainless steel 316 and cobalt chrome.

And Hammond also adds that SLS “ticks a lot of green boxes”. “With reductive manufacturing, you can lose up to 90% of the material, but we only use the amount of material that you need.”